RESUMEN
This study unveiled the early cellular and molecular events induced by 1,2-dimethylhydrazine (DMH) in the colon and liver and their implications on pre- and neoplastic lesion burden in a late timepoint. Male Wistar rats received four DMH injections (40 mg/kg body weight) for 2 weeks and were sacrificed 24 h (short-term study) or 22 (medium-term study) weeks after the last DMH administration. In the short-term study, DMH led to increased leukocyte (comet assay) and colon (H2AX) genotoxicity, enhanced proliferation (Ki-67) and apoptosis (caspase-3) indexes in both liver and colon. Furthermore, the expression of mRNA (Cat, Gsta1, Gsta2, Gpx1, Gstm1, Sod1, Sod2 and Sod3) and the activity of antioxidant agents were diminished in the colon and liver of DMH-induced rats, eliciting an environment of oxidative stress featuring elevated lipid hydroperoxide levels. Apoptosis effectors were upregulated in the liver (Bax, Casp3 and Fas), and developmental genes were downregulated in both colon and liver (Foxa1, Foxa2, Smad2 and Smad4). In the medium-term study, DMH led to a high number of preneoplastic colonic aberrant crypt foci and tumors (adenomas and invasive adenocarcinomas) but few preneoplastic hepatic glutathione S-transferase (GST-P)-positive foci. Our novel gene expression data highlights overlooked mechanisms in the liver (main metabolizing organ) and colon (main target organ) on toxicity and carcinogenesis induced by repeated doses of DMH, as both organs should be considered in further interventions on the initiation stage of colon carcinogenesis.
Asunto(s)
1,2-Dimetilhidrazina/toxicidad , Carcinógenos/toxicidad , Colon/efectos de los fármacos , Neoplasias del Colon/inducido químicamente , Neoplasias Hepáticas/inducido químicamente , Hígado/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Daño del ADN/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Mutágenos/toxicidad , Ratas , Ratas WistarRESUMEN
Maslinic acid triggers compelling antiproliferative and pro-apoptotic effects in different human cancer cell lines. Hence, the chemopreventive activity was investigated on early stages of carcinogenesis induced by 1,2-dimethylhydrazine (DMH) which is a model that mimics human sporadic colorectal cancer. Male Sprague-Dawley rats were orally administered either maslinic acid at 5, 10 or 25 mg/kg dissolved in (2-hydroxypropyl)-ß-cyclodextrin 20% (w/v) or the solvent for 49 days. After one week of treatment, animals received three weekly intraperitoneal injections of DMH at the dose of 20 mg/kg. Maslinic acid reduced the preneoplastic biomarkers, aberrant crypt foci (ACF) and mucin-depleted foci (MDF), already at 5 mg/kg in a 15% and 27%, respectively. The decline was significant at 25 mg/kg with decreases of 33% and 51%, respectively. Correlation analysis showed a significant association between the concentrations of maslinic acid found in the colon and the reduction of ACF (r = 0.999, P = 0.019) and MDF (r = 0.997, P = 0.049). The present findings demonstrate that maslinic acid induced an inhibition of the initiation stages of carcinogenesis. The assessment of this pentacyclic triterpene at the colon sheds light for designing diets with foods rich in maslinic acid to exert a chemopreventive activity in colorectal cancer.
Asunto(s)
1,2-Dimetilhidrazina/toxicidad , Focos de Criptas Aberrantes/prevención & control , Neoplasias del Colon/prevención & control , Olea/química , Extractos Vegetales/farmacología , Lesiones Precancerosas/prevención & control , Triterpenos/farmacología , Focos de Criptas Aberrantes/inducido químicamente , Focos de Criptas Aberrantes/patología , Animales , Carcinógenos/toxicidad , Neoplasias del Colon/inducido químicamente , Neoplasias del Colon/patología , Masculino , Lesiones Precancerosas/inducido químicamente , Lesiones Precancerosas/patología , Ratas , Ratas Sprague-DawleyRESUMEN
SCOPE: To investigate the effect of pomegranate mesocarp, a polyphenol-rich by-product of juice production, in colorectal cancer (CRC) chemoprevention. METHODS AND RESULTS: A mesocarp decoction (PMD) is administered for 6 weeks in the diet to Pirc rats, mutated in Apc, a key-gene in CRC. Mucin-depleted foci (MDFs), as CRC biomarkers, are reduced in PMD-fed rats compared to controls (MDF/colon: 34 ± 4 versus 47 ± 3, p = 0.02). There is an increase in apoptosis in MDFs from PMD-treated rats compared to controls (2.5 ± 0.2 versus 1.6 ± 0.2, p < 0.01). To elucidate the involved mechanisms, two colon-relevant metabolites of the polyphenolic and fiber PMD components, urolithin-A (u-A) and sodium butyrate (SB), are tested alone or in combination in vitro (colon cancer cells), and ex vivo in adenoma (AD) and normal mucosa (NM) from Pirc rats. u-A 25 µm plus SB 2.5 mm (USB) causes a significant reduction in COX-2 protein expression compared to untreated controls (about -70% in cancer cell cultures, AD, and NM), and a strong increase in C-CASP-3 expression in cells (about ten times), in AD and NM (+74 and +69%). CONCLUSION: These data indicate a chemopreventive activity of PMD due, at least in part, to pro-apoptotic and anti-inflammatory action of its metabolites that could be exploited in high-risk patients.
Asunto(s)
Anticarcinógenos/química , Anticarcinógenos/farmacología , Neoplasias Colorrectales/prevención & control , Mucosa Gástrica/efectos de los fármacos , Lythraceae/química , Adenoma/tratamiento farmacológico , Adenoma/patología , Proteína de la Poliposis Adenomatosa del Colon/genética , Animales , Apoptosis/efectos de los fármacos , Ácido Butírico/farmacología , Proliferación Celular/efectos de los fármacos , Colitis/tratamiento farmacológico , Colitis/patología , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/patología , Cumarinas/farmacología , Células HCT116 , Células HT29 , Humanos , Ratas Endogámicas F344 , Ratas MutantesRESUMEN
Considerable evidence suggests that environmental factors, including diet and cigarette smoke, are involved in the pathogenesis of colon cancer. Carcinogenic nitroso compounds (NOC), such as N-nitrosodimethylamine (NDMA), are present in tobacco and processed red meat, and NOC have been implicated in colon cancer. Azoxymethane (AOM), commonly used for experimental colon carcinogenesis, is an isomer of NDMA, and it produces the same DNA adducts as does NDMA. Heterocyclic aromatic amines (HAAs) formed during the combustion of tobacco and high-temperature cooking of meats are also associated with an elevated risk of colon cancer. The most abundant carcinogenic HAA formed in tobacco smoke is 2-amino-9H-pyrido[2,3-b]indole (AαC), whereas 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) is the most potent carcinogenic HAA formed during the cooking of meat and fish. However, the comparative tumor-initiating potential of AαC, MeIQ, and AOM is unknown. In this report, we evaluate the formation of DNA adducts as a measure of genotoxicity, and the induction of colonic aberrant crypt foci (ACF) and dysplastic ACF, as an early measure of carcinogenic potency of these compounds in the colon of male A/J mice. Both AαC and AOM induced a greater number of DNA adducts than MeIQ in the liver and colon. AOM induced a greater number of ACF and dysplastic ACF than either AαC or MeIQ. Conversely, based on adduct levels, MeIQ-DNA adducts were more potent than AαC- and AOM-DNA adducts at inducing ACF. Long-term feeding studies are required to relate levels of DNA adducts, induction of ACF, and colon cancer by these colon genotoxicants.
Asunto(s)
Azoximetano/toxicidad , Colon/efectos de los fármacos , Aductos de ADN/efectos de los fármacos , Quinolinas/toxicidad , Animales , Peso Corporal/efectos de los fármacos , Carcinógenos/toxicidad , Colon/patología , Aductos de ADN/análisis , Hígado/efectos de los fármacos , Hígado/patología , Masculino , Ratones Endogámicos , Mucinas/metabolismo , Pruebas de Toxicidad SubcrónicaRESUMEN
PIRC rats (F344/NTac-Apc (am1137) ) mutated in the Apc gene spontaneously develop colon tumors thus mimicking familial adenomatous polyposis (FAP) and sporadic colorectal cancer (CRC) more closely than Apc-based rodent models developing tumors mostly in the small intestine. To understand whether microscopic dysplastic lesions precede the development of macroscopic tumors, PIRC rat colon was examined for the presence of mucin depleted foci (MDF), microadenomas of the rodent and human colon. Few MDF (about 4/animal) were already present in 1-month-old rats and their number rapidly increases to about 250 in 8-month-old rats. These lesions showed Wnt signaling activation (nuclear ß-catenin accumulation) and were dramatically decreased by sulindac (320 ppm), a drug with chemopreventive activity (MDF/rat at 4 months: 156 ± 8 and 38 ± 6 in controls and sulindac-treated rats, respectively, means ± SE, p < 0.001). Since altered proliferation and apoptosis could underlie the early phases of carcinogenesis, we studied these processes in the apparently normal colon mucosa (NM) of 1-month-old PIRC and wt rats. Colon proliferation (PCNA expression) was significantly higher in PIRC rats. Notably, PIRC rat NM showed resistance to apoptosis since it sustained proliferation and had lower apoptosis after a cytotoxic insult with 1,2 dimethylhydrazine. Gene expression of Myc, p21, Birc5, Ogg1, Apex1 and Sod2 were significantly up-regulated in the NM of PIRC rat. The overall results put forward PIRC rat as useful model of colon carcinogenesis, either to study the process itself or to test in vivo chemopreventive agents in both short- and long-term studies.
Asunto(s)
Apoptosis , Neoplasias del Colon/etiología , Pólipos del Colon/patología , Genes APC , Mucinas/fisiología , Mutación , Animales , Proliferación Celular , Colon/patología , Neoplasias del Colon/patología , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/fisiología , Femenino , Genes myc , Masculino , Proteínas Asociadas a Microtúbulos/fisiología , Ratas , Ratas Endogámicas F344 , Sulindac/farmacología , SurvivinRESUMEN
Chemoprevention opens new window in the prevention of all types of cancers including colon cancer. Aloin, an anthracycline in plant pigment, can be utilized as a protective agent in cancer induction. In the present study, we have evaluated the chemopreventive efficacy of aloin against 1,2-dimethylhydrazine (DMH)-induced preneoplastic lesions in the colon of Wistar rats. DMH-induced aberrant crypt foci (ACF) and mucin-depleted foci (MDF) have been used as biomarkers of colon cancer. Efficacy of aloin against the colon toxicity was evaluated in terms of biochemical estimation of antioxidant enzyme activities, lipid peroxidation, ACF, MDF, histopathological changes, and expression levels of molecular markers of inflammation and tumor promotion. Aloin pretreatment ameliorates the damaging effects induced by DMH through a protective mechanism that involved reduction in increased oxidative stress enzymes (p < 0.001), ACF, MDF, cyclooxygenase-2, inducible nitric oxide synthase, interleukin-6, proliferating cell nuclear antigen protein expression, and tumor necrosis factor-α (p < 0.001) release. From the results, it could be concluded that aloin clearly protects against chemically induced colon toxicity and acts reasonably by inducing antioxidant level, anti-inflammatory and antiproliferative markers.
Asunto(s)
1,2-Dimetilhidrazina/toxicidad , Enfermedades del Colon/inducido químicamente , Enfermedades del Colon/prevención & control , Emodina/análogos & derivados , Lesiones Precancerosas/inducido químicamente , Lesiones Precancerosas/prevención & control , Animales , Antioxidantes/metabolismo , Emodina/farmacología , Regulación Enzimológica de la Expresión Génica , Masculino , Ratas , Ratas WistarRESUMEN
Type 2 diabetes mellitus (T2DM) and insulin resistance (IR) increase colon cancer risk. Antidiabetic drugs stabilizing incretin hormones, such as inhibitors of dipeptidyl peptidase-4 activity (DPP4i), may affect colon carcinogenesis; however, the data remain controversial. Therefore, the authors studied whether long-term administration of the DPP4i Sitagliptin (SITA) affects 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis. Male F344 rats fed a high-fat (HF) diet promoting colon carcinogenesis and IR, were induced with DMH (100 mg/kg × 2 times). One week later, the animals were allocated to two groups: one continuing with HF diet (controls; n = 8) and one receiving SITA (n = 8) mixed in the diet (260 ppm). Body weight, food consumption and glycemia were not affected by SITA. Fifteen weeks after DMH, the number of the precancerous lesions mucin-depleted foci (MDF) was significantly lower in rats treated with SITA [MDF/colon: 9.5 ± 0.9 and 6.4 ± 0.9 in controls (n = 8) and SITA groups (n = 8), respectively; means ± SE, p < 0.05]. Reactive oxygen species in the blood were also significantly lower in the SITA group [6.75 ± 0.69 and 5.63 ± 0.75 (H2 O2 in mM) in controls (n = 5) and SITA (n = 6), respectively; means ± SE, p < 0.05]. Rats treated with SITA had a lower DPP4 activity in the intestine but not in the plasma. Intestine growth morphometric parameters and colon proliferation, as proliferating cell nuclear antigen expression, were not affected by SITA. In conclusion, the results suggest a protective effect of DPP4i against colon carcinogenesis that could be exploited in chemoprevention trials.